>>return a select distinct UserID …. In the first post 1, 2, 3, 4 are UserIds from one table.Step1: 2 OR 3 --> Both recordsStep2: 2 AND 4 --> if both exists then only those two recordsStep3: 1 AND AboveRecords (output of above two conditions) --> If 1 is also exists then include those records in outputStep4: Step3 output OR 4 --> Step3 User Ids and 4 to be included in final output...